Name:   Orca or Killer Whale (Orcinus orca).  

(Southern resident population of the Pacific Northwest)

(Dolphin Family)                                           

 

 

 

 

Photo courtesy of Center for Biological Diversity

 

Status:            State (WA) and Federal Endangered. 

 

Description:   The largest members of the Dolphin family, Orcas are toothed whales with one blowhole, and a distinct black and white coloration.  They are often a top predator in their respective ecosystems.  Female Orcas can reach a length of up to 25.26 feet (7.7 meters) and males can reach a length of up to 29.52 feet (9.0 meters). 

 

Distribution and Relations Between Populations:   Orcas are distributed worldwide, although the southern resident population is of special interest in this document.  Orcas of the Pacific Northwest are classified into three distinct forms: offshores, transients, and residents.  These forms all differ in morphology, ecology, behavior, and genetic composition (Baird 1999).  Less is known about the offshore than the resident or transient populations.  The offshore form apparently lives along the shores and open ocean areas of the Pacific, ranging from southeast Alaska to California.  The population of the offshore orcas in the Pacific Northwest is estimated to be between 200 and 300 individuals (NMFS 1999).  The habitat of the transient population ranges from the waters of southeast Alaska to California.  Their population is estimated to be about 300 individuals (Center for Whale Research).  Transients tend to feed on marine mammals while the resident form tends to feed primarily on fish (Morton 1990).  The resident form is divided into two genetically and morphologically distinct populations: the northern residents and the southern residents (Bigg et al. 1987, Baird and Stacey 1988, Bain 1989, Ford et al. 1998, Hoelzel et al. 1998, Matkin et al. 1998).  The northern resident population consists of approximately 200 individuals in 16 pods (Ford et al. 2000).  Their habitat ranges from the Northern Georgia strait on the coast of B.C. to the waters Southeast Alaska (Ford et al. 1994).  Mitochondrial DNA analysis indicates that the Northern Residents associates and interbreeds with other resident – type populations to the north thereby maintaining a healthy genetic stock (Dahlheim et al. 1997, Hoelzel et al. 1998).  The northern residents and southern residents have partially overlapping habitats and share more ecological and behavioral characteristics compared to any other orca population, yet genetic analysis indicates that the two populations do not interbreed (Baird & Stacey 1988, Stevens et al. 1989, Hoelzel and Dover 1991).  In fact, genetic evidence indicates that the Southern Resident orca population is completely reproductively isolated (Hoelzel et al. 1998).

            The habitat of the southern resident population ranges from the waters of Southern Vancouver Island to the Srait of Juan De Fuca and the Puget Sound (Ford et al. 1994).  They have also been spotted at Monterey Bay in California (Center for Biological Diversity 2001).  This population is currently divided into three pods: the J pod, the K pod, and the L pod.  The J pod is the only pod seen on a semi-regular basis in the Puget Sound during the winter, and is most frequently seen along the western shore of San Juan Island (Heimlich – Boran 1988, Osborne 1999).  The K pod is most frequently seen during May and June on the west shore of San Juan Island.  The L pod, being the largest southern resident pod of all, frequently breaks off into smaller groups and it is very rare to see the entire pod traveling together (Ford et al. 1994, Center for Biological Diversity 2001).  The J pod has 19 members, the K pod has 16 members, and the L pod has 47 members (Center for Whale Research). 

Map courtesy of Ford et al. 1994

Threats:         A major threat to the Southern Residents is toxic pollution, especially from organochlorides such as PCB’s, DDT, and dioxins.  PCBs are found in much higher concentrations than DDT dioxins in the tissues of southern resident Orcas (Ross et al. 2000).  According to the EPA, the Puget sound basin has 16 superfund sites containing PCBs.  7 of these sites are known to have contaminated marine and/or freshwater ecosystems (Center for Biological Diversity 2001, App. D).  The concentrations of bio-accumulative organochlorides are also very high and have been increasing in the Puget Sound (McCain et. al. 2000).  Adult members of the southern resident population have PCB contamination levels that exceed the immunological effects threshold established for seals (Ross et al. 2000).  No viral epidemics have yet been recorded in this population, however, organochloride contamination has been linked to outbreaks among other whale populations in the Atlantic and Mediterranean (Simmonds and  Mayer 1997).

A major dietary component of the Southern Residents are Pacific salmon species, especially Chinook salmon (Center for Biological Diversity 2001).  Over-harvesting and the degradation of habitat has greatly depleted salmon stocks.  The Puget Sound chinook salmon was listed as threatened under the ESA in march of 1999 (National Marine Fisheries Service 2000).  There is a concern that the depletion of salmon stocks could force the Southern Resident Orcas to change their feeding habits to eat increasing amounts of less “desirable” fish such as bottom feeding fish.  Bottom feeders, having higher concentrations of bioaccumulants would deliver a greater load of toxins to the whales when eaten (Taylor 2001). 

Boat traffic is yet also a potential threat to the survival of the Southern Residents.  The frequency of boats, including recreational whale watching vessels within the habitat of the Southern Residents has increased dramatically in recent years.  Several studies have been conducted to assess the effect of boat traffic on Orcas.  While these studies have documented short-term effects, long-term effects remain uncertain (Trites & Bain 2000).  However, the noise level of boats around this population is close to the critical level assumed to cause permanent hearing loss over a prolonged exposure (Erbe 2000).  Most of the whale watching vessels on the water is non-commercial and non-licensed.  Most of theses “freelance” whale watchers tend to be more likely to violate established whale watching guidelines, simply because they are not aware (Center for Biological Diversity 2001). 

 

Population Trends: The Southern resident population numbered at an approximate estimation of 110 individuals in the mid – 1960’s.  Since then, it has experienced three major declines.  Between 1967 and 1972, approximately 34 Southern Residents were captured live for public display.  As a result, this population was numbered at 67 during the July 1973 census period (Center for whale Research).  The live captures themselves altered the sex and age ratio of the population to create a significant reproductive gap.  So after the population rebounded to a peak population of 83 in 1980 it then declined a second time to 74 in 1984.  This second decline was essentially an echo of the previous (Center for Biological Diversity 2001).  The L pod seemed to be the most affected during this period while the J pod appeared to be unaffected.  Again the population rebounded a second time to reach a population of 97 in 1996.  From 1996 to 2001 the population declined a third time to a population of 78 individuals (Center for whale Research).  This third decline is at the approximate rate of 4.9% per year.  It is especially alarming to researchers because it is caused by an unexplained increase in mortality of all age and sex classes without a substantial reduction in calving (Taylor 2001, Center Biological Diversity 2001). 

            All members of this population have been photographed and cataloged since 1976 by the center for whale research.  Below is a graph of this population from the beginning of this study to the present.

Data courtesy of Center for whale Research

 

Links for Additional information:

 

The Center for Biological Diversity
 http://www.biologicaldiversity.org/swcbd/species/orca/index.html#

 

The Center for Whale Research

http://www.whaleresearch.com/

 

NMFS: the Puget Sound Chinook Salmon Listed as Threatened webpage

 http://www.nwr.noaa.gov/1salmon/salmesa/chinpug.htm

 

References:

 

Bain, D.E. 1989.  An evaluation of evolutionary processes: studies of natural selection, dispersal, and cultural evolution: Killer whales (Orcinus orca).  Ph.D. Dissertation, University of California, Santa Cruz.

 

Baird, R.W. 1999.  Status of Killer Whales in Canada.  Contract report to the Committee on the Status of Endangered Wildlife in Canada (C.O.S.E.W.I.C.), Ottawa.

 

Baird, R.W. and P.J. Stacey.  1988.  Variation in saddle patch pigmentation in populations of Killer Whales (Orcinus orca) from British Columbia, Alaska, and Washington State.  Canadian Journal of Zoology 66:2582-2585.

 

Bigg, M.A.,  G.M. Ellis,  J.K.B. Ford, and K.C. Balcomb.  1987.  Killer Whales: a study of their identification, genealogy, and natural history in British Columbia and Washington State.  Phantom Press. Nanaimo, B.C.

 

Center for Biological Diversity.  2001.  Petition to list the Southern Resident Killer Whale (Orcinus orca) as an endangered species under the Endangered Species Act.  Center for Biological Diversity, Berkley CA.

 

Center for Whale Research  http://www.whaleresearch.com/

 

Dahlheim, M.E., D.K. Ellifrit,  and  J.D. Swenson. 1997.  Killer Whales of Southeast Alaska: a catalogue of photo-identified individuals.  Day Mon Press, Seattle.

 

Erbe, C.,  2000.  Underwater Noise of Whale Watching Boats and its Effects on Marine Mammals.  IWC Scientific Report SC/52/WW11,  Presented to the WORKSHOP ON ASSESSING THE LONG TERM EFFECS OF WHALE WHATCHING ON CETACEANS,  International Whaling Commission, 13-13  June, 2000,  Adelaide, Australia.

 

Ford, J.K.B.,  G.M. Ellis,  L.G. Barrett-Lennard,  A.B. Morton,  R.S. Palm,  and  K.C. Balcomb.  1998.  Dietary specialization in two sympatric populations of Killer Whales (Orcinus orca) in coastal British Columbia and adjacent waters.  Canadian Journal of Zoology 77:  2000.

 

Ford, J.K.B., G.M. Ellis, and K.C. Balcomb. 1994. Killer Whales: The Natural History and Genealogy of Orcinus orca in British Columbia and Washington State.  Vancouver , UBC Press.

 

Ford, J.K.B., G.M. Ellis, and K.C. Balcomb. 2000. Killer Whales: The Natural History and Genealogy of Orcinus orca in British Columbia and Washington State. 

 

Heimlich-Boran, J.R.  1988.  Behavioral Ecology of Killer Whales (Orcinus orca) in the Pacific Northwest.  Canadian Journal of Zoology 66:565-578.

 

Hoelzel, A.R., and G.A. Dover, 1991.  Genetic Differentiation Between Sympatric Killer Whale Populations.  Journal of Heredity 66:191-195.

 

Hoelzel, A.R.,  M. Dahlheim,  and  S.J. Stern. 1998.  Low genetic variation among killer whales (Orcinus orca) in the eastern North Pacific, and genetic differentiation between foraging specialists.  Journal of Heredity 89:121-128.

 

Kruse, S. 1991.  The interactions between killer whales and boats in Johnstone Strait, B.C. In K. Pryor and K.S. Norris (eds). Dolphin societies.  University of California Press, Berkeley.

 

Matkin, C.O.,  D. Schel,  G. Ellis,  L. Barrett-Lennard,  H. Jurk,  and  E. Saulitis.  1998.  Comprehensive killer whale investigation,  Exxon Valdez oil spill restoration project annual report (Restoration project 97012).  North Gulf Oceanic Society, Homer, Alaska.

 

McCain, B.B., et al.  2000.  National Benthic Surveillance Project: Pacific Coast.  Organic Chemical Contaminants Cycles I to VII (1984 – 1990).  NOAA, Seattle.

 

Morton, A.B.  1990.  A quantitative comparison of the behavior of resident and transient forms of the Killer Whale off the central British Columbia coast.  Reports of the International Whaling Commission Special Issue 12:245-248.

 

National Marine Fisheries Service.  March, 1999.  Chinook salmon (Oncorhynchus tshawytscha) puget sound esu listed threatened.  webpage.  http://www.nwr.noaa.gov/1salmon/salmesa/chinpug.htm

 

National Marine Fisheries Service.  1999.  Stock assesment for the Killer Whale (Orcinus orca): Eastern North Pacific Southern Resident Stock.

 

Osborne, R.W. 1991.   Historical Ecology of Salish Sea “Resident” Killer Whales (Orcinus orca): With Implications for Management.  Ph.D. dissertation, Department of Geography, University of Victoria.

 

Ross, P.S.  G.M. Ellis,  M.G. Ikonomu,  L.G. Barrett-Lennard,  R.F. Addison.  2000 (in press).  High PCB concentrations in free ranging Pacific Killer Whales, Orcinus Orca: effects of age, sex and dietary preference.  Marine Pollution Bulletin. 40:504-515.

 

Simmonds, M., and S.J. Mayer. 1997. An evaluation of environmental and other factors in some recent marine mammal mortalities in Europe: implications for conservation and management. Environmental Reviews 5:89-98.

 

Stevens, T.A.,  D.A. Duffield,  E.D. Asper,  K.G. Hewlett,  A. Bolz,  L.J. Gage,  and  G.D. Bossart.  1989.  Preliminary findings of restriction fragment differences in mitochondrial DNA among Killer Whales (Orcinus orca).  Canadian Journal of Zoology 67:2592-2595.

 

Taylor, Martin and Brent Plater.  2001.  Population Viability Analysis for the Southern Resident Population of the Killer Whale (Orcinus orca).  The Center For Biological Diversity.  Tucson, Arizona.

 

Trites, A.W.,  D.E. Bain.  2000.  Short and Long term Effects of whale Watching on Killer Whales (Orcinus orca) in British Columbia.  University of British Columbia, Vancouver B.C.  and  Six Flags Marine World Vallejo, Vallejo, Ca.

 

Last updated September 1, 2001

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